Pseudomonas aeruginosa is an opportunistic bacterial pathogen that is capable of causing fatal acute lung infections in critically ill individuals (1). The ability of the bacterium to damage the lung epithelium has been linked with the expression of toxins that are directly injected into eukaryotic cells via a type III-mediated secretion and translocation mechanism (2, 3).
The proteins encoded by the P. aeruginosa type III secretion and translocation apparatus demonstrate a high level of amino acid identity with members of the Yersinia Yop regulon (4-6). Of all the type III systems discovered in Gram-negative bacteria, only P. aeruginosa possesses a homologue to the Yersinia V antigen, PcrV (see 6 for review of type III systems). Homologous proteins to the secretion and translocation apparatus are encoded by both plant and animal pathogenic bacteria. These organisms include human pathogens such as Salmonella typhimurium, Shigella flexneri, Enteropathogenic E. coli, Chlamydia spp., and plant pathogens such as Xanthamonas campestris, Pseudomonas syringae, Erwinia amylovora and Ralstonia solanacearum. However, only P. aeruginosa and Yersinia encode the V antigen.
Yahr, et al., 1997, discloses the sequence of the operon encoding PcrV and compares the sequence to the LcrV protein. Thus, the amino acid sequence of PcrV is known and is available under accession number AF010149 of GenBank.